1. Field of the Invention
The present invention relates to a still camera which forms an image of a target object and obtains digital image data, and which then compresses this digital data for storage upon a recording medium.
2. Description of the Related Art
A still camera is per se known from the prior art which records an image of a target object as digital image data upon a recording medium such as a memory card. With this type of still camera, light from the target object is focused by a photographic lens upon a photoelectric conversion element in an imaging section. Analog image data which are photoelectrically converted by the photoelectric conversion element is converted into digital data by an A/D conversion device. Various forms of signal processing are performed upon this digital image data, and the data is then temporarily stored in a buffer memory. This stored data is then compressed and is recorded upon a memory card.
For example, in a still camera disclosed in Japanese Patent Laid-Open Publication Serial No. Heisei 3-205963, the digital image data is compressed by a compression ratio which is suitable in practice, and with which the compression coefficient is selected so that the amount of data after compression should be as small as possible. Alternatively, the compression coefficient may be selected so that the amount of data after compression is always a constant amount.
However, with still cameras of the prior art type described above, the time period from the start of the photographic process until the completion of storage of the image data upon the memory card becomes rather long, and when several photographs are to be taken in sequence (so called sequential photography) it has become a primary factor in preventing increase of speed. Further, the operation of the circuits for data analysis in order to select the compression ratio, and the operation of the compression circuitry, are wasteful of electrical power.